To elaborate a bit...DME, the bus transportation system, is a 24/7 deal. It may run a bit less frequently after 8:00 pm, but you will get to your resort. But, the RAC system (remote airline checkin) does not run 24/7. They open at 5am and close at 1pm (or thereabouts). You have to be completely checked in, no less than 3 hrs. before flight time. So, if you have an 8am flight departure, you can't use RAC. But, you can check in up to 12 hrs before flight departure time.
I mention this because many people confuse the two entities, and put them both under the auspices of DME. Then, someone wants to check their bags for their 7 am flight and are distressed to find they aren't able to use 'DME', but it's RAC they can't use!